标题： 塑料晶体中巨大压卡效应的分子起源 显示英文标题

标题： Molecular origins of colossal barocaloric effects in plastic crystals

摘要： 近年来，取向无序晶体或塑性晶体由于其温度诱导的分子有序-无序相变相关的显著潜热和熵变，已改变了固态冷却领域，这种相变在外部场刺激下可以产生巨大的卡诺效应。 然而，这些巨大卡诺效应的分子机制仍不明确，且缺乏增强卡诺塑性晶体性能的一般原则。 以往的研究主要集中在分子旋转上，忽视了其他可能至关重要的因素，如晶格振动和分子构型。 在本研究中，我们采用经典分子动力学（MD）模拟来复制和阐明在典型塑性晶体新戊二醇（NPG）中实验观察到的巨大压卡（BC）效应——由静水压力驱动的效应——的微观起源。 我们的MD模拟表明，在NPG中，由晶格振动和分子构型产生的联合BC响应和相变熵变几乎等于分子重取向产生的，分别贡献了45%和55%。 这些发现表明，除了直接影响分子旋转动力学的氢键外，晶格振动和分子结构特征往往被忽视，必须纳入先进卡诺塑性晶体的合理设计和建模中。 这些见解不仅具有重要的基础兴趣，而且对推动下一代固态制冷技术的发展至关重要。 显示英文摘要

摘要： In recent years, orientationally disordered crystals, or plastic crystals, have transformed the field of solid-state cooling due to the significant latent heat and entropy changes associated with their temperature induced molecular order-disorder phase transition, which can produce colossal caloric effects under external field stimuli. However, the molecular mechanisms underlying these huge caloric effects remain inadequately understood, and general principles for enhancing the performance of caloric plastic crystals are lacking. Previous studies have predominantly focused on molecular rotations, overlooking other potentially critical factors, such as lattice vibrations and molecular conformations. In this study, we employ classical molecular dynamics (MD) simulations to both replicate and elucidate the microscopic origins of the experimentally observed colossal barocaloric (BC) effects -- those driven by hydrostatic pressure -- in the archetypal plastic crystal neopentyl glycol (NPG). Our MD simulations demonstrate that in NPG, the combined BC response and phase-transition entropy changes arising from lattice vibrations and molecular conformations are nearly equal to those from molecular reorientations, contributing 45% and 55%, respectively. These findings suggest that, alongside hydrogen bonding -- which directly impacts molecular rotational dynamics -- lattice vibrational and molecular structural features, often overlooked, must be integrated into the rational design and modeling of advanced caloric plastic crystals. These insights are not only of significant fundamental interest but also essential for driving the development of next-generation solid-state refrigeration technologies.